So I’m reading Roy Blount Jr.’s latest book “Hail, Hail, Euphoria,” which is sort of a written commentary to go along with the 1933 Marx Brothers movie “Duck Soup,” and he gets to a scene that is excerpted in another film, Woody Allen’s 1986 “Hannah and Her Sisters.” And Roy goes on for a page an a half about how “Duck Soup” helped convince Woody’s character, Alvy Singer, not to kill himself.

Now, I’ve always enjoyed Roy Blount Jr. on such NPR programs as “Wait Wait ... Don’t Tell Me!” and, occasionally, “A Prairie Home Companion.” And I’m an avid fan of the films of both the Marx Brothers and Woody Allen. So this part of the book should have been a rare entertainment trifecta: An enjoyable writer turning his attention to the intersection of two unique comedic filmmakers: A team of brothers from 75 years ago and an auteur of today.

And yet — are there any sharp-eyed Woody Allen fans who can guess why I was suddenly distracted from my reveries? That’s right: Alvy Singer was the character Woody Allen played in “Annie Hall”; his character’s name in “Hannah and Her Sisters” was Mickey.

Now, I’ll grant that Woody Allen pretty much plays the same character from one film to the next; there are fewer distinctions between his performances in, say, “Play It Again, Sam” and “Small Time Crooks,” to pick two films at random, than between Robert De Niro’s in, say, “Raging Bull” and “The King of Comedy.” It’s not that Woody can’t act. He was nominated for a best actor Academy Award in 1978 (for his performance as Alvy Singer in “Annie Hall,” of all parts), giving him more Oscar nominations than Donald Sutherland, Jim Carrey, Bob Hope, both Douglas Fairbanks and, yes, Groucho Marx combined.

Still, Mr. Blount’s oversight is surprising given the attention to detail he pays to all other aspects of the movie.

For the uninitiated (and if you’re among them, hie thee to a DVD player and initiative thyself), “Duck Soup” is the Marx Brothers at their peak. Their two previous movies were “Monkey Business” and “Horse Feathers”; their next two would be “A Night at the Opera” and “A Day at the Races.” They were on a roll.

“Duck Soup,” while a commercial dud when released, stands up better than any of their films today. Perhaps because the usual supporting-character love story and musical numbers weren’t shoehorned in; perhaps because the anarchy is inspired; perhaps because the much of humor still works: Harpo on a battlefield, carrying a sandwich board that reads, “Join the Army and see the Navy”; Groucho, gesturing toward the regal Margaret Dumont: “Remember, men, we’re fighting for his woman’s honor; which is probably more than she ever did.” And, of course, the famous mirror scene.

Blount is a fan’s fan. He has read the original “Duck Soup” script (working title: “Firecrackers.”). He seems to know the filmography of every cast member (Ambassador Trentino of Sylvania is played by Louis Calhern, who, we learn, “will go on to portray the distinguished American jurist Oliver Wendell Holmes in ‘The Magnificent Yankee.'”). He is a font of Marxian minutiae, offering scholarly dissertations on everything from Groucho’s walk to a sour-grapes facial expression known as the Gookie.

So to misidentify the Woody Allen character seems improbably out of character. I’ve even looked for some signal it was intentional. After all, in “Duck Soup,” after Harpo runs into the mirror, the glass inexplicably disappears. And in “Annie Hall,” when Alvy performs at the University of Wisconsin, there is a New York State flag on the stage.

Maybe Roy is paying homage. Or maybe he was just trying to get some dumb columnist to notice the error and point it out. In which case, I owe him a Gookie.